Method of and apparatus for milling soap and similar plasticizable material



Nov. 8, 955 D. E. MARSHALL 2,723,242

METHOD OF AND APPARATUS FOR MILLING SOAP AND SIMILAR PLASTICIZABLE MATERIAL Filed June 30, 1951 4 Sheets-Sheet 1 I I I I I I I I I I I I I I I l I I I I I I I I I I I I I I I I II III] LLL LLLLLLLLLLLLLL LLLL. fi I 14141111114741.1111 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I VL /W Nov. 8, 1955 V- 1955 D. E. MARSHALL 2,723,242

METHOD OF D APPARA FOR MILLING SOAP AND S: LAR PLAST ZABLE MATERIAL Filed June 30, 1951 4 Sheets-Sheet 3 Adv Nov- 8. 1955 D. E. MARSHALL 2,723,242

METHOD OF AND APPARATUS FOR MILLING SOAP AND SIMILAR PLASTICIZABLE MATERIAL Filed June 50, 1951 4 Sheets-Sheet 4 United States Patent lVIETHOD OF AND APPARATUS FOR MILLING SOAP AND SINIILAR PLASTICIZABLE MATE- RIAL Donald E. Marshall, Edina, Minn., assignor to Micro Processing Equipment Inc., Des Plaines, 111., a corporation of Illinois Application June 30, 1951, Serial No. 234,614

7 Claims. (Cl. 252367) This invention relates to a method of and apparatus for milling soap and similar plasticizable material and is closely related to the invention of the pending application of Donald B. Marshall, Serial No. 129,942, filed November 29, 1949, now Patent No. 2,619,680, issued December 2, 1952.

That application discloses and broadly claims a novel technique for converting plastic materials, and especially soap, by mechanical manipulation in an attrition mill characterized by a carrier band traveling at high speed through a closely fitted milling channel.

The present invention also utilizes such a high speed carrier band but improves upon this earlier scheme particularly in the way in which the material to be milled is fed to the milling chamber and onto the band, with the result that materials having poor flow characteristics, such as very low moisture soap, chocolate and similar materials are handled more efficiently.

As in the aforesaid copending application, the attrition or mechanical manipulation of the material undergoing treatment is accomplished by repeatedly subjecting the same to a high speed shearing and compacting action brought about by the coaction between the opposite sides of the carrier band and the adjacent walls of the channel which extend along the length of the hand. These walls are spaced from the sides of the band a distance on the order of between one-thousandth (.001) and five-thousandths (.005) of an inch, and in the present invention have transverse grooves therein which not only produce the desired surface configuration for the walls of the milling chamber or channel as they did before, but have the additional function of simultaneously feeding small increments of the material onto the band. The grooves feed the material onto the band in successive layers, each of which is but a few ten-thousandths of an inch thick; and as the coated band moves past the succession of grooves and the lands therebetween, it is alternately turbulated and subjected to intense shearing and compacting forces with the result that upon leaving the milling zone the material is ultrarefined.

The pressure required to feed the material to the milling zone and onto the band, of course, depends upon the viscosity of the material. Very low moisture soaps, for instance on the order of five percent moisture content, chocolate, plastics and the like, require extremely high feeding pressures, often exceeding 1000 pounds per square inch to feed the material to the milling zone. These excessive pressures must be accommodated without imposing excessive braking pressure upon the carrier band, and it is, therefore, one of the purposes of this invention to provide an improved method and apparatus of the character described by which the required high feeding pressures may be employed to bring the material to the entrance of the milling zone and to feed the same into the milling zone and onto the band without undue braking effect upon the band.

More specifically it is an object of this invention to so feed the material into the milling zone and onto the "ice carrier band that as the material enters the milling zone a substantial pressure reduction is effected so that the hydrostatic pressure of the material on the band is greatly less than it is in the inlet passages through which the material is fed to the entrance of the milling zone.

Another object of this invention is to so feed the material into the milling chamber and onto the carrier band that the rate of the input substantially equals the capacity of the mill to efl ect the desired attrition and to discharge the milled material therefrom.

In the aforesaid copending application the inlet passage through which the material moves to the milling zone or chamber is so disposed with respect to the milling chamber that the incoming material enters along one edge of the carrier band, and while both edges of the band are spaced from the adjacent walls of the milling chamber so that a hydrostatic pressure balance obtains in the feed chamber, the pressure within the feed chamber is the same as it is within the inlet passage. Consequently an increase in the pressure employed to advance the material through the inlet passages is reflected in a corresponding increase in braking action upon the carrier band.

By contrast the present invention not only feeds the materials into the milling zone or chamber simultaneously at both edges of the carrier band, but in addition effects a substantial reduction in hydrostatic pressure as the material passes into the milling chamber.

Another distinction between the instant invention and that of the aforesaid copending application resides in the fact that in the present invention the milled'material is allowed to discharge at the entrance of the carrier band into the milling chamber as well as at its exit from the milling chamber. This arrangement lessens the braking load upon the carrier band at its entrance into the milling chamber, since by allowing some counterfiow of the material the pressure on the band at this point does not build up like it does where no counterflow is permitted.

With a view toward assuring maximum through-put capacity and minimum braking action upon the carrier band, this invention has as still another object to provide the milling surfaces which oppose the opposite sides of the carrier band with a novel arrangement of grooves which, by their cross sectional size, shape and placement assure rapid delivery of the incoming material across the entire width of the band and at the same time define a succession of milling areas across which the band moves and with which it cooperates to subject the material to an intense shearing and compacting action.

As will appear more fully hereinafter, it is desirable that the material leaving the mill be in granular form as distinguished from flakes, and to this end the present invention has as a further object to provide grooves in the wall surfaces between which the band runs which are specially designed and located to effect the desired granulation of the material as it discharges from the mill.

A still further object of this invention is to provide an improved manner of cleaning the carrier band which involves a novel structural relationship between the band and a pair of rotary discs between which the band runs, like those shown in the copending application of Donald E. Marshall and John A. Harrington, Serial No. 216,042, filed March 16, 1951.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel method and apparatus hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come Within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and modifications of certain features of the apparatus, and in which:

Figure 1 is a view diagrammatically illustrating a milling apparatus of the type to which this invention pertains;

Figure 2 is .a cross sectional view through the milling chamber or channel and material inlet manifold of the apparatus taken on the line 2-2 of Figural but at an enlarged scale and turned 90 degrees for convenience;

Figure ,3 is a longitudinal sectional .view through the milling chamber or channel substantially on the planes of the line 3.-3 in Figure 2 and with intermediate portions broken away;

Figure 4 is a sectional view through Figure 3 on the plane of the line 4...4;

Figure 5 is a fragmentary detail view illustrating a slightly modified form of grooving in the milling surfaces across which the carrier band moves;

Figure 6 is a fragmentary detail sectional view similar to the lower portion of Figure'3 but illustrating an an rangement of r s groo s de gn d to bre k p he material into granules as :it discharges from the mill-ing chamber; a

Figure '7 is a perspective view of the disc structure by which the milled material is cleaned from the carrier band as it emerges from the milling channel; and

Figure 8 is a detail cross sectional view through the hand taken on the plane of the line 8-8 in Figure 7 to show the novel relationship between the bandand cleaning discs.

As in the aforesaid copending application the method of this invention involves mechanical manipulation of the material to be milled, produced by subjecting it to an intense shearing and compacting action between the opposite faces of a fast moving carrier band and two closely spaced milling surfaces between which the band travels.

.In the aforesaid application the material was fed onto the carrier band and into the milling zone from a feeding zone in open unrestricted communication with the inlet manifold or duct through which the material entered the feeding zone under pressure; and since the band traveled through the feeding zone whatever hydrostatic pressure existed therein was applied directly on the band with the result that as the feed pressure was in creased the braking action on :the band became excessive.

In the present invention the feeding and milling zones are in effect one and are connected with the inlet manifold only through .a pair of Opp sed constricted slits each of which extends for the full length .of the combined feeding and milling zone and connects the same with an elongated entrance zone or chamber extend- "ing along one edge of the combined milling and feeding that no part of the band is gripped by the material in the entrance zones or chambers.

Upon entry into the combined feeding and milling zones the material is uniformly distributed over the opposite faces of the carrier band so that the pressure of the material on the band is uniform across its entire width and over the entire length of that portion of the band within the zone. To secure such uniform distribution of the material over the entire surface of the band the opposedmilling surfaces between which the band travels have closely spaced'transverse grooves therein-whichopen at their ends to the restricted entrance passages and are of-sufiiciently large cross section as to preclude measurable line loss .pressure reduction.

like.

Thus to recapitulate, the method of this invention consists essentially in the following steps:

(1) Pressure feeding the, material to be milled into a restricted milling zone simultaneously from two opposite directions;

(2) Subjecting the material in the milling zone to a high speed shearing and compacting action by rapidly moving a carrier band lengthwise through the milling zone in a direction crosswise to the direction in which the material is fed into the milling zone and with the edges of the carrier band facing the incoming material;

(3) Effecting a drop in the hydrostatic pressure of the material as it enters the milling zone and before it contacts the carrier band; and

(4) Discharging the milled material from the milling zone along the opposite surfaces of the carrier band at least at the exit of the carrier band from the milling zone and, if desired, also at the entrance of the band into the milling zone.

An apparatus especially adapted to carry out the foregoing method is illustrated in the accompanying drawings and reference is now more particularly directed thereto.

As in the aforesaid copending application, the apparatus consists essentially of an endless carrier band 10 trained about a pair of spaced pulleys and 12 so as to have one stretch of the band travel downwardly in a straight line path through a milling chamber or channel indicated generally by the numeral 13. Suitable means (not shown) are provided to drive atleast one of the pulleys. The milling chamber or channel 13 comprises an elongated casing composed of two base sections 14 and 15 bolted together with a pair of milling plates 16 therebetween.

The plates 16 are in juxtaposition to one another and the space therebetween provides the combined feeding and milling zone referred to hereinbefore through which the carrier band 10 travels. Preferably the plates 16 are formed of metal having good heat conductivity characteristics and, if desired, may be cored out to provide for the circulation of a cooling fluid.

As best seen in Figure 2 the-carrier band 10 is narrower than the plates 16 so that the edges of the band are spaced in from the adjacent edges of the plates. The spaces between these edge portions of the plates constitute restricted entrance passages 17 leading into the combined feeding and milling zone from two' elongated entrance zones 18. The entrance zones 18 are formed by apair of opposed cavities in the-base sections 14 and 15, and extend for the major portion of the length of the base sections.

Beyond the upper and lower ends of the entrance zones 18, the base sections 14 and 15 meet except where they are cut away toaccommodate the plates '16. Those portions of the plates 16 encompassed by the entrance zones 18 and the restricted entrance passages 17 have their adjacent milling surfaces provided withtransverse grooves 19.

These grooves are preferably herring-bone shaped and extend from the side edges of the plates '16 toward the center at a suitable downward angle of 45 degrees or the At their ends the grooves open to the restricted entrance passages 17 and by virtue of the inward and downward slant cause the material which enters from the entrance zones to move toward the centerofthe band simultaneously from both edges thereof. The grooves 19 thus collectively feed the material from the restricted entrance passages 17 across both side surfaces of that portion of the band lying within the compass of these grooves so that collectively the grooves .19 in effect form the feeding chamber while the lands 20 between them .define thesides of the milling chamber.

small capacity of each individual groove, a multi-layer s coating is built up on the band, each layer of which is but a few ten-thousandths of an inch thick. This loading of the band requires only relatively light pressure, just enough to assure the material moving quickly down the grooves.

As the ribbon of material coating each side surface of the band moves across the lands 20 it is subjected to the ntense shearing and compacting action which characterizes the milling accomplished with this invention and that of the aforesaid copending application. From tests it appears that the zone of greatest shear in this ribbon layer is only a fraction of the space between the band and the tops of the lands. For example, with a clearance of .005 inch, which is 125 microns, the zone of maximum shear is no more than microns, or one-twelfth the total space; and, of course, as the action progresses the grooves rapidly and successively expose all of the ribbon mass to the intense shearing zone.

Milling is also effected beyond the ends of the milling zone defined collectively by the grooves and lands, where the adjacent surfaces of the milling plates 16 have much smaller and more closely spaced grooves 21 extending at right angles across the path of the band, and attention is directed to the fact that there are approximately twice as many of these smaller grooves 21 at the downstream end of the milling chamber, that is at the point of egress of the band from the milling chamber, as there are at the upstream end.

Roughly, therefore, the resistance to the discharge of the material from the milling chamber is balanced at the top and bottom, though it is preferable that the seal be somewhat more effective at the top or point of ingress of the band. In any event during operation, the material discharges at the point of ingress of the band as well as at the point of egress and while the material discharging at the top or inlet is not as important production-wise, it does have the advantage of dissipating heat.

The material to be milled is fed to the entrance zones 18 by a'force pump 22 or its equivalent. Any suitable means may be employed to feed the material to the pump through its inlet pipe 23; and a manifold 24 connected to the discharge end of the pump distributes the discharge thereof over the length of the elongated milling chamber or channel 13. The several branches of this manifold are connected to a header plate 25 which in turn is bolted to the back of the base section 15. The header plate 25 has inlet passages 26 which lead to the elongated entrance zones 18 at a number of places. In the present instance there are three manifold branches and three points of entry into the entrance zones 18, though Figures 3 and 4 show only one, those portions of these views which ordinarily would show the endmost entry ports being broken away and not illustrated. It is, of course, important that the inlet passages 26 and also the manifold 24 be so shaped and dimensioned as to assure a minimum of restriction to flow.

As brought out hereinbefore in the description of the method, considerable pressure is necessary to feed the material into the entrance zones 18 especially if the material being handled has poor flow characteristics as, for instance, low moisture soap. In such cases the hydrostatic pressure of the material in the entrance zones may be 500, 1000 or even 5000 pounds per square inch, but in view of the substantial constriction which the entrance passages 17 present, the hydrostatic pressure of the material at the time it comes into contact with the carrier band is greatly reduced from what it is in the entrance zones. This is important since it enables the desired mechanical manipulation of the material without danger of imposing heavy power consuming braking loads upon the band.

The ideal condition would be one where the band picked up an increment of material at each groove 19 without any appreciable drag or friction on the band. Therefore, to minimize power losses the pressure at the pick-up points 6 (the grooves 19) should be no greater than needed td build up a ribbon on each side surface of the band.

On soap this feed pressure at the band surface maybe quite low, 10 pounds per square inch ordinarily being suflicient. Greater pressure will increase the feed somewhat, but at the expense of milling efiiciency. Therefore, the optimum condition is a pressure where the soap is being takenaway just as fast as it is supplied to the band surface. The grooves 19 do this when designed properly for the material being processed. The larger their cross section, the less pressure needed to cause the material to flow into the center of the band.

On 10 percent moisture soap at F. temperature and a hydrostatic pressure in the entrance zones of 500 pounds per square inch, a groove cross sect1on of inch by inch proved correct for a 3 inch wide band set at a milling clearance of .005 inch. With these conditions approximately 100 pounds of soap will enter the mill every hour for each inch of feed chamber length.

The cross sectional shape of grooves 19 may be square for most situations; though certain variations may be used, as for instance, undercutting the groove so that the base or root is larger than the top. This increases the piping capacity of the groove without increasing the area of contact between the band surfaces and the material 1n the grooves. Such an undercut groove, however, has the disadvantage of tending to clog. Most applications will favor the simpler square cross section.

Another variation in the design of the grooves is shown in Figure 5 Whereinthe grooves 19' are square in cross section but increase in Width and depth toward the center of the band to offset line loss and assure the maintenance of uniform pressure across the full width of the band.

From the description thus far it will be evident that the present invention provides a greatly increased output and maximum product refinement for a minimum expenditure of power, and hence a minimum generation of heat which must be dissipated. Such heat as is developed can be easily removed by circulating a fluid coolant through passages in the milling plates as mentioned hereinbefore or by cooling either the input material, the carrier band, or the air entrained with the material as it enters the milling channel, or by using such channel width, length and band clearance dimensions that the amount of work done in one pass does not exceed the heat regulating facilities.

The capacity of a given mill can be ascertained by determining the volume of the ribbon transported by the carrier band per unit of time. Thus, for instance, assuming a band speed of 10,000 feet per minute, a band width of 4 inches and a ribbon layer of material of onethousandth of an inch; under such circumstances 57,600 cubic inches or 33.35 cubic feet of material will be obtained from one hour of band travel. Soap, as it leaves the band mill, has a density of between 50 and 60 pounds per cubic foot as an unbroken layer Which means that at a capacity of 33.35 cubic feet per hour the output stated in pounds would be approximately 1,800 pounds per hour.

The foregoing computations were predicated upon a clearance of .005 inches between the band and each channel wall. Hence, the theoretical conveyor capacity is five times 33.35 cubic feet per hour or, stated in another way, the band speed could be reduced to one-fifth of the 10,000 feet per minute and still have the capacity to deliver 33.35 cubic feet per hour.

Though as indicated hereinbefore, the milled product leaves the milling chamber or channel at both ends, that is at the point of ingress of the carrier band as well as at its point of egress, production-wise it is preferable to so balance the seals at the top and bottom that the bulk of the material discharges at the bottom and it has been found that if the lowermost grooves 21 which last contact the soap as it discharges from the milling chamber are deeper than the grooves 21 and V-shaped with the larfis therebetween coming to an edge, the materialand especially soap-is broken up into tiny flakes as it discharges from the mill. An arrangement of grooves Such as this is illustrated in Fig. 6, and as will be readily under.- stood the small flake-like pieces into which the discharging material is broken all have the same thickness established before subdivision by the clearance between adjacent milling surfaces. This subdivision of the material results in a product which in a sense may be said to be granulated.

, Much of the milled material, however, adheres to the band and must be removed therefrom. This is effectively acocmplished by'the disc-type cleaner illustrated in the copending application of Donald E. Marshall and John A. Harrington, Serial No. 216,042, filed March 16, 1951. This disc-type cleaner comprises a pair of dished discs 30, at least the peripheral portions of which are resilient. These discs oppose one another and are mounted to revolve about an axis so positioned that the band, upon leaving the milling channel, passes chordwise across and between the discs as clearly shown in Figure 7. Any suitable means may be used to revolve the discs at a speed so related to .the band speed that slippage between the band and discs is reduced to a minimum. Usually the discs are spring loaded, i. e. pressed together, so as to tightly grip the band. This obviates a special drive for the discs since by their right grip on the band they are spun by the movement of the band itself.

Since the band is formed of a high quality steel it may be relatively thin and although the discs are quite resilient and tend to conform themselves to the band as explained in the aforesaid copending application, Serial No. 216,042, the effectiveness of the'cleaning device is improved by tapering the edges of the band as at 31. By .so feather-edging the band the peripheries of the cleaning discs snugly wrap around the band as shown in Figure 8 to thereby assure quick removal of all adhering ever, that the illustration in Figure 8 is not in true proportion, the band and clearances having been greatly exaggerated for the sake of clarity. I

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in the art that this invention provides an improved method and apparatus for milling soap and similar plasticizable materials and that it accomplishes unprecedented output with a minimum power requirement.

What I claim as my invention is:

l. A method of milling soap and other plastici zable material, which comprises: feeding the material to be milled at high pressure into an elongated feeding zone; by said pressure forcing the material from the feeding zone along the entire length thereof and simultaneously in opposing directions into an elongated milling zone communicated with the feeding zone along the entire length thereof so that the material enters the milling zone from opposite directions; effecting a substantial drop in the internal pressure of the material as it passes from the feeding zone and enters the milling zone; subjecting the material in the milling zone to a high speed shearing and compacting action; and discharging the milled material from theelongated milling zone.

2. Apparatus for milling soap and other plasticizable material, comprising: means defining an elongated restrict material from the band. It should be appreciated, howed milling zone including opposed closely spaced walls;

a carrier band;rneans mounting thecarrier band for movement-of a stretchthereofendwise through the milling zone and between said opposed walls with the opposite faces of .the band in close juxtaposition to said walls so as to coact therewith in effecting the desired attrition; means defining an elongated entrance chamber alongside the milling chamber and opposite each edge of the band; means defining a constricted,elongatedpassage :from each entrance chamber into the milling chamber so that ,material .fed to' the entrance chambers under high pressure .has its internal pressure reduced as it flows through the constricted passages .into the milling chamber; and said opposed walls of the milling chamber having grooves th e n 91m ns t said pnstr ted pa ag s an e endin ,919.5 h? ssss the w lls, sai oov s distributin i 9 Iii-31P u formly QYFI. the app a e of the ca r e bead. and iii? use the e s n en ast g with the band to effect the desired attrition.

APPMQW r milling was and oth r pl c zab ma e al, jcqm r si a me n defin n a l at d m ing l ber ha in a Pa f DPPQSit l y pa a a ier band having a'thickness slightly less than the d t c b tw n aid Pair Wa s; m a mo n h carrier band for endwise movement of a stretch thereof throu h e e on ated m ll gv c amb r om on end t e e 01 P e wi t e .b s su st ial equi pa ed m aid awe Walls; mean definin a r lat y a ge -y ll hambcr' xt ndi en w of t e, depar ed lims ha h an along ea h eas o th a ri r ban m an efining r st c d communica i Passa e sading from each entry chamber along the length thereof to I be spread over the faces of the carrier band.

4. An attrition mill, CQHIPIlSlHg? a pair of opposed elongated walls spaced apart a slight distance; a band movable ,endwise through the space between said walls with band traveling lengthwise of said walls and its side edges spaced in from the, adjacent edges of the walls, the. clearance between the walls and the adjacent faces of the band together defining a milling zone, and the spaces between said side edge portions of the walls beyond the opposite edges of the band providing elongated constricted slit-like entrance passages into the .milling zone, one alongside each edge of the band and coextensive in length/with the milling zone; means defining an elongated feed chamber in open communication with each of said entrance pas sages, said feed chambers being largeandunrestricted proportion to the constricted entrance passages;'. and

means for forcing the material to be milled tosaid Ifeed chambers and thereby causing the material to'flow simul: taneously through both of said elongated constricted entrance passages and to enter the milling zonesimultane- 'ously from its opposite sides and along the entire length thereof but at considerably reduced pressure by virtue of the pressure reduction effected by the constriction of the entrance passages.

5. A method of milling soap and other plasticizable material, which comprises; moving an elongated milling surface longitudinally across a complementary sta tit inary milling surface of substantial length and with vyer yisilig ht clearance'between said surfaces, the space between .said surfaces defining a milling zone; feeding the material to be milled at very high pressure to a feeding zone which has constricted communication with said milling zone for the full length thereof and at opposite sides thereof; by

said pressure forcing the material to be milled from the feeding zone into the milling zone simultaneously ,from the opposite sides of the milling zone and along thefiill length thereof so that the forces imposed upon themilling surfaces by the pressure of the. incoming material are balanced; effectinga drop in the internal pressure of .the material as it passes from the feeding zone into the milling zone; rapidly distributing the-material entering the milling zone over the complementary millingsurfaces; by'therelative movement of the closely adjacent milling surfaces subjecting the material inthe milling zone to intense shearing and compacting; anddischarging the milled rnaterial from the milling zone. I

6. Apparatus for milling soap and other Iplasticizab le material, comprising: cooperating stationary and movable milling elements having milling surfaces; means mounting said milling elements and constraining them to relative movement with their milling surfaces opposing one another in closely spaced relation to define a milling zone; wall means fixed with respect to the stationary milling member and defining a large capacity passage having an inlet for the material to be milled, said wall means being shaped to provide constricted communication between said passage and the milling zone at opposite sides of said zone so that material may flow from said passage into the milling zone simultaneously from opposite sides thereof whereby a balanced material feed into the milling zone may be had; and means for feeding the material to be milled under high pressure into said large capaicty passage to thereby cause the material to move into the milling zone simultaneously from opposite sides thereof and by its passage through the constricted communication between the passage and the milling zone have its pressure greatly reduced before it comes into contact with the moving milling element.

7. The milling apparatus of claim 6 further characterized by the provision of grooves in the milling surface of one of the milling elements opening at their ends to the constricted communication between the passage and the milling zone to provide flow paths along which the material entering the milling zone may move to efiect rapid distribution of the material over the complementary milling surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 743,955 Thompson Nov. 10, 1903 2,082,819 Beccard June 8, 1937 2,146,770 Schwantes Feb. 14, 1939 2,494,891 Marshall Jan. 17, 1950 2,619,680 Marshall Dec. 2, 1952 

1. A METHOD OF MILLING SOAP AND OTHER PLASTICIZABLE MATERIAL, WHICH COMPRISES: FEEDING THE MATERIAL TO BE MILLED AT HIGH PRESSURE INTO AN ELONGATED FEEDING ZONE; BY SAID PRESSURE FORCING THE MATERIAL FROM THE FEEDING ZONE ALONG THE ENTIRE LENGTH THEREOF AND SIMULTANEOUSLY IN OPPOSING DIRECTIONS INTO AN ELONGATED MILLING ZONE COMMUNICATED WITH THE FEEDING ZONE ALONG THE ENTIRE LENGTH THEREOF SO THAT THE MATERIAL ENTERS THE MILLING ZONE FROM OPPOSITE DIRECTIONS; EFFECTING A SUBSTANTIAL DROP IN THE INTERNAL PRESSURE OF THE MATERIAL AS IT PASSES FROM THE FEEDING ZONE AND ENTERS THE MILLING ZONE; SUBJECTING THE MATERIAL IN THE MILLING ZONE TO A HIGH SPEED SHEARING AND COMPACTING ACTION; AND DISCHARGING THE MILLED MATERIAL FROM THE ELONGATED MILLING ZONE.
 6. APPARATUS FOR MILLING SOAP AND OTHER PLASTICIZABLE MATERIAL, COMPRISING: COOPERATING STATIONARY AND MOVABLE MILLING ELEMENTS HAVING MILLING SURFACES; MEANS MOUNTING SAID MILLING ELEMENTS AND CONSTRAINING THEM TO RELATIVE MOVEMENT WITH THEIR MILLING SURFACES OPPOSING ONE ANOTHER IN CLOSELY SPACED RELATION TO DEFINE A MILLING ZONE; WALL MEANS FIXED WITH RESPECT TO THE STATIONARY MILLING MEMBER AND DEFINING A LARGE CAPACITY PASSAGE HAVING AN INLET FOR THE MATERIAL TO BE MILLED, SAID WALL MEANS BEING SHAPED TO PROVIDE CONSTRICTED COMMUNICATION BETWEEN SAID PASSAGE AND THE MILLING ZONE AT OPPOSITE SIDES OF SAID ZONE SO THAT MATERIAL MAY FLOW FROM SAID PASSAGE INTO THE MILLING ZONE SIMULTANEOUSLY FROM OPPOSITE SIDES THEREOF WHEREBY A BALANCED MATERIAL FEED INTO THE MILLING 